1. Field of the Invention
The invention generally relates to a buffer and more particularly to a dual voltage buffer with current reuse.
2. Related Art
Analog-to-digital converters (ADCs) may be utilized in a variety of integrated circuit (IC) implementations. One such use is to digitize received signals in wireless communication. For example, an ADC may be utilized to convert radio frequency (RF) signals received by an antenna into digital signals. ADCs generally include voltage buffers to provide reference voltages to other circuitry in the ADC. In modern circuit design, especially for portable applications or applications with otherwise set maximum power dissipation limits, limiting the current used in analog parts of the circuit can be very important to reduce power consumption and heat generation. However, a voltage buffer usually requires a high current to provide low output impedance.
Furthermore, to reduce power consumption, reduce heat generation, and comply with physical limits of technology, power supply voltages are constantly being lowered in advanced modern CMOS technologies. To be able to maintain the operation of bias sections of voltage buffers in a lowered power supply environment, the driven voltages may have to be very close to each other and near the middle of the available voltage range. However, many applications of such driven voltages (including in an ADC) require a relatively wide voltage differential.
Therefore, a need arises for a voltage buffer that can provide a relatively wide voltage differential using a relatively low current.